From 3e5d8f978435bb9ba4dfe3f4514e65e7885db1a9 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Tue, 13 Jan 2009 20:41:35 +0900 Subject: x86: make percpu symbols zerobased on SMP [ Based on original patch from Christoph Lameter and Mike Travis. ] This patch makes percpu symbols zerobased on x86_64 SMP by adding PERCPU_VADDR() to vmlinux.lds.h which helps setting explicit vaddr on the percpu output section and using it in vmlinux_64.lds.S. A new PHDR is added as existing ones cannot contain sections near address zero. PERCPU_VADDR() also adds a new symbol __per_cpu_load which always points to the vaddr of the loaded percpu data.init region. The following adjustments have been made to accomodate the address change. * code to locate percpu gdt_page in head_64.S is updated to add the load address to the gdt_page offset. * __per_cpu_load is used in places where access to the init data area is necessary. * pda->data_offset is initialized soon after C code is entered as zero value doesn't work anymore. This patch is mostly taken from Mike Travis' "x86_64: Base percpu variables at zero" patch. Signed-off-by: Tejun Heo Signed-off-by: Ingo Molnar --- arch/x86/kernel/head64.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'arch/x86/kernel/head64.c') diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c index b9a4d8c4b93..bc2900ca82c 100644 --- a/arch/x86/kernel/head64.c +++ b/arch/x86/kernel/head64.c @@ -44,6 +44,8 @@ void __init x86_64_init_pda(void) { _cpu_pda = __cpu_pda; cpu_pda(0) = &_boot_cpu_pda; + cpu_pda(0)->data_offset = + (unsigned long)(__per_cpu_load - __per_cpu_start); pda_init(0); } -- cgit v1.2.3 From f32ff5388d86518c0375ccdb330d3b459b9c405e Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Tue, 13 Jan 2009 20:41:35 +0900 Subject: x86: load pointer to pda into %gs while brining up a CPU [ Based on original patch from Christoph Lameter and Mike Travis. ] CPU startup code in head_64.S loaded address of a zero page into %gs for temporary use till pda is loaded but address to the actual pda is available at the point. Load the real address directly instead. This will help unifying percpu and pda handling later on. This patch is mostly taken from Mike Travis' "x86_64: Fold pda into per cpu area" patch. Signed-off-by: Tejun Heo --- arch/x86/kernel/head64.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'arch/x86/kernel/head64.c') diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c index bc2900ca82c..76ffba2aa66 100644 --- a/arch/x86/kernel/head64.c +++ b/arch/x86/kernel/head64.c @@ -26,8 +26,8 @@ #include #include -/* boot cpu pda */ -static struct x8664_pda _boot_cpu_pda; +/* boot cpu pda, referenced by head_64.S to initialize %gs for boot CPU */ +struct x8664_pda _boot_cpu_pda; #ifdef CONFIG_SMP /* -- cgit v1.2.3 From c8f3329a0ddd751241e96b4100df7eda14b2cbc6 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Tue, 13 Jan 2009 20:41:35 +0900 Subject: x86: use static _cpu_pda array _cpu_pda array first uses statically allocated storage in data.init and then switches to allocated bootmem to conserve space. However, after folding pda area into percpu area, _cpu_pda array will be removed completely. Drop the reallocation part to simplify the code for soon-to-follow changes. Signed-off-by: Tejun Heo Signed-off-by: Ingo Molnar --- arch/x86/kernel/head64.c | 12 ------------ 1 file changed, 12 deletions(-) (limited to 'arch/x86/kernel/head64.c') diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c index 76ffba2aa66..462d0beccb6 100644 --- a/arch/x86/kernel/head64.c +++ b/arch/x86/kernel/head64.c @@ -29,20 +29,8 @@ /* boot cpu pda, referenced by head_64.S to initialize %gs for boot CPU */ struct x8664_pda _boot_cpu_pda; -#ifdef CONFIG_SMP -/* - * We install an empty cpu_pda pointer table to indicate to early users - * (numa_set_node) that the cpu_pda pointer table for cpus other than - * the boot cpu is not yet setup. - */ -static struct x8664_pda *__cpu_pda[NR_CPUS] __initdata; -#else -static struct x8664_pda *__cpu_pda[NR_CPUS] __read_mostly; -#endif - void __init x86_64_init_pda(void) { - _cpu_pda = __cpu_pda; cpu_pda(0) = &_boot_cpu_pda; cpu_pda(0)->data_offset = (unsigned long)(__per_cpu_load - __per_cpu_start); -- cgit v1.2.3 From 1a51e3a0aed18767cf2762e95456ecfeb0bca5e6 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Tue, 13 Jan 2009 20:41:35 +0900 Subject: x86: fold pda into percpu area on SMP [ Based on original patch from Christoph Lameter and Mike Travis. ] Currently pdas and percpu areas are allocated separately. %gs points to local pda and percpu area can be reached using pda->data_offset. This patch folds pda into percpu area. Due to strange gcc requirement, pda needs to be at the beginning of the percpu area so that pda->stack_canary is at %gs:40. To achieve this, a new percpu output section macro - PERCPU_VADDR_PREALLOC() - is added and used to reserve pda sized chunk at the start of the percpu area. After this change, for boot cpu, %gs first points to pda in the data.init area and later during setup_per_cpu_areas() gets updated to point to the actual pda. This means that setup_per_cpu_areas() need to reload %gs for CPU0 while clearing pda area for other cpus as cpu0 already has modified it when control reaches setup_per_cpu_areas(). This patch also removes now unnecessary get_local_pda() and its call sites. A lot of this patch is taken from Mike Travis' "x86_64: Fold pda into per cpu area" patch. Signed-off-by: Tejun Heo Signed-off-by: Ingo Molnar --- arch/x86/kernel/head64.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) (limited to 'arch/x86/kernel/head64.c') diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c index 462d0beccb6..1a311293f73 100644 --- a/arch/x86/kernel/head64.c +++ b/arch/x86/kernel/head64.c @@ -26,12 +26,18 @@ #include #include -/* boot cpu pda, referenced by head_64.S to initialize %gs for boot CPU */ +#ifndef CONFIG_SMP +/* boot cpu pda, referenced by head_64.S to initialize %gs on UP */ struct x8664_pda _boot_cpu_pda; +#endif void __init x86_64_init_pda(void) { +#ifdef CONFIG_SMP + cpu_pda(0) = (void *)__per_cpu_load; +#else cpu_pda(0) = &_boot_cpu_pda; +#endif cpu_pda(0)->data_offset = (unsigned long)(__per_cpu_load - __per_cpu_start); pda_init(0); -- cgit v1.2.3 From 9939ddaff52787b2a7c1adf1b2afc95421aa0884 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Tue, 13 Jan 2009 20:41:35 +0900 Subject: x86: merge 64 and 32 SMP percpu handling Now that pda is allocated as part of percpu, percpu doesn't need to be accessed through pda. Unify x86_64 SMP percpu access with x86_32 SMP one. Other than the segment register, operand size and the base of percpu symbols, they behave identical now. This patch replaces now unnecessary pda->data_offset with a dummy field which is necessary to keep stack_canary at its place. This patch also moves per_cpu_offset initialization out of init_gdt() into setup_per_cpu_areas(). Note that this change also necessitates explicit per_cpu_offset initializations in voyager_smp.c. With this change, x86_OP_percpu()'s are as efficient on x86_64 as on x86_32 and also x86_64 can use assembly PER_CPU macros. Signed-off-by: Tejun Heo Signed-off-by: Ingo Molnar --- arch/x86/kernel/head64.c | 2 -- 1 file changed, 2 deletions(-) (limited to 'arch/x86/kernel/head64.c') diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c index 1a311293f73..e99b661a97f 100644 --- a/arch/x86/kernel/head64.c +++ b/arch/x86/kernel/head64.c @@ -38,8 +38,6 @@ void __init x86_64_init_pda(void) #else cpu_pda(0) = &_boot_cpu_pda; #endif - cpu_pda(0)->data_offset = - (unsigned long)(__per_cpu_load - __per_cpu_start); pda_init(0); } -- cgit v1.2.3 From b12d8db8fbfaed1e8222a15333a3645599636854 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Tue, 13 Jan 2009 20:41:35 +0900 Subject: x86: make pda a percpu variable [ Based on original patch from Christoph Lameter and Mike Travis. ] As pda is now allocated in percpu area, it can easily be made a proper percpu variable. Make it so by defining per cpu symbol from linker script and declaring it in C code for SMP and simply defining it for UP. This change cleans up code and brings SMP and UP closer a bit. Signed-off-by: Tejun Heo Signed-off-by: Ingo Molnar --- arch/x86/kernel/head64.c | 10 ---------- 1 file changed, 10 deletions(-) (limited to 'arch/x86/kernel/head64.c') diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c index e99b661a97f..71b6f6ec96a 100644 --- a/arch/x86/kernel/head64.c +++ b/arch/x86/kernel/head64.c @@ -26,18 +26,8 @@ #include #include -#ifndef CONFIG_SMP -/* boot cpu pda, referenced by head_64.S to initialize %gs on UP */ -struct x8664_pda _boot_cpu_pda; -#endif - void __init x86_64_init_pda(void) { -#ifdef CONFIG_SMP - cpu_pda(0) = (void *)__per_cpu_load; -#else - cpu_pda(0) = &_boot_cpu_pda; -#endif pda_init(0); } -- cgit v1.2.3 From 004aa322f855a765741d9437a98dd8fe2e4f32a6 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Tue, 13 Jan 2009 20:41:35 +0900 Subject: x86: misc clean up after the percpu update Do the following cleanups: * kill x86_64_init_pda() which now is equivalent to pda_init() * use per_cpu_offset() instead of cpu_pda() when initializing initial_gs Signed-off-by: Tejun Heo Signed-off-by: Ingo Molnar --- arch/x86/kernel/head64.c | 7 +------ 1 file changed, 1 insertion(+), 6 deletions(-) (limited to 'arch/x86/kernel/head64.c') diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c index 71b6f6ec96a..af67d3227ea 100644 --- a/arch/x86/kernel/head64.c +++ b/arch/x86/kernel/head64.c @@ -26,11 +26,6 @@ #include #include -void __init x86_64_init_pda(void) -{ - pda_init(0); -} - static void __init zap_identity_mappings(void) { pgd_t *pgd = pgd_offset_k(0UL); @@ -96,7 +91,7 @@ void __init x86_64_start_kernel(char * real_mode_data) if (console_loglevel == 10) early_printk("Kernel alive\n"); - x86_64_init_pda(); + pda_init(0); x86_64_start_reservations(real_mode_data); } -- cgit v1.2.3 From 8ce031972b40da58c268caba8c5ea3c0856d7131 Mon Sep 17 00:00:00 2001 From: Brian Gerst Date: Mon, 19 Jan 2009 12:21:27 +0900 Subject: x86: remove pda_init() Impact: cleanup Copy the code to cpu_init() to satisfy the requirement that the cpu be reinitialized. Remove all other calls, since the segments are already initialized in head_64.S. Signed-off-by: Brian Gerst Signed-off-by: Tejun Heo --- arch/x86/kernel/head64.c | 2 -- 1 file changed, 2 deletions(-) (limited to 'arch/x86/kernel/head64.c') diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c index af67d3227ea..f5b27224769 100644 --- a/arch/x86/kernel/head64.c +++ b/arch/x86/kernel/head64.c @@ -91,8 +91,6 @@ void __init x86_64_start_kernel(char * real_mode_data) if (console_loglevel == 10) early_printk("Kernel alive\n"); - pda_init(0); - x86_64_start_reservations(real_mode_data); } -- cgit v1.2.3